PUBLICATIONS:
1. Khaled Almustafa, “Performance of Multiple Input Multiple Output Communication System in Partially Known Channels,” Ph.D. Thesis. The University of Western Ontario. 2007.
2. Serguei Primak, Khaled Almustafa, Jeff Weaver and Valeri Kontorovich, “On Moment Analysis of Stochastic Differential Equations with Random Structure,” Dynamics of Continuous, Discrete and Impulsive Systems journal, 2007.
ABSTRACT
Modeling of signals and interference in the field of communications, radar, sonar, and speech processing is usually based on the assumptions that the processes may be considered to be stationary and that experimental estimations of their simplest statistical characteristics such as Autocovariance Function and Probability Density Function are available. While the generation of stationary random processes (sequences) with a specified density does not present any principal difficulty, the solution of the joint problem requires much more effort. Some researchers use the way to generate these specific PDF using some sequential combinations of linear filtering and zero memory non-linear transformations of white Gaussian noise [48]. A different approach is based on the treatment of the process with the desired characteristics as a stationary solution of the proper system of Stochastic Differential Equations excited by White Gaussian Noise. This thesis deals with numerical simulation of such equations and applies the developed techniques to practical communications problems. A MATLAB tool kit has also been developed.
3. Primak S, Almustafa K, Willink T and Baddour K, “On Achievable Data Rates and Optimal Power Allocation in Fading Channels with Imperfect Channel State Information,” Wireless Personal Communication Journal, 2008.
ABSTRACT
Achievable rates of wireless communication systems with pilot-based channel estimation are investigated for the case of time-selective fading. Novel analytical expressions for the maximum achievable rates of such systems are derived in terms of the system signal-to-noise ratio (SNR), fading rate and estimation scheme deployed. The frame size is optimized jointly based on the SNR and the fading rate. The maximum rate achieving coding scheme is suggested and shown to be a modified version of the classical water-filling algorithm that accounts for imperfect channel state information (CSI) at the transmitter. The impact of the estimation scheme and the angular spread of the received signal on the quality of estimation and achievable rates is evaluated. A number of numerical simulations are provided to illustrate the dependence of the optimal block length and achievable rates on SNR, fading rate, estimation scheme and angular spread of the channel.
4. Khaled Almustafa, “Numerical Solutions of Stochastic Differential Equations (SDE) and Their Applications in Wireless Communication,” Master Thesis. The University of Western Ontario. 2005.
CONFERENCES:
1. Khaled Almustafa, Rached N. Zantout, Hasan R. Obeid and Fadi Sibai “Recognizing Characters in Saudi License Plates Using Character Boundaries,” Proceeding Innovations 2011, Abudabi, UAE
ABSTRACT
In this paper character recognition in Saudi Automobile License Plates is described. Due to special properties of Saudi license plates, simpler procedures as compared to the ones used for Lebanese plates have been developed. A limited character set for recognition enables the development of smaller recognition trees. The developed procedure was applied to different characters taken from real license plates and the recognition rate was 100% for characters supported by the algorithm. Uniformly distributed pseudo-random noise was added to simulate error in the image. The algorithm was proven to work even in cases in which the characters were extremely degraded by noise.
2. Hasan R. Obeid, Khaled Almustafa, Rached N. Zantout, Fakhry Khellah, “ Saudi License Plate Localization Using Object Adjacency Properties,” Proceeding ICCIT2011, Aqabah, Jordan.
ABSTRACT
In this paper, the “object adjacency” approach to vehicle license plate localization is adapted to locating Saudi license plates. The approach identifies potential candidates of license plate characters in an image and calculates distances between those objects and identifies their relative positions. This information is used to identify possible groupings (series) of characters that may be part of a license plate. The relative positions of the series and their contents are then used to confirm (or deny) the existence of a Saudi license plate. The algorithm was successfully applied to images containing Saudi License plates. The results of the tests are also discussed in this paper
3. Khaled Almustafa, Rached N. Zantout, Hasan R. Obeid, "Peak Position, Recognizing Characters in Saudi License Plates," Proceedings GCC2011 Dubai, UAE.
ABSTRACT
In this paper character recognition in Saudi Automobile License Plates is described. Due to special properties of Saudi license plates, simpler procedures as compared to the ones used for Lebanese plates have been developed. A limited character set for recognition enables the development of smaller recognition trees. The process relies on processing pixels along vertical and horizontal lines taken across the character. The developed procedure was applied to different characters taken from real license plates and the recognition rate was 100% for characters supported by the algorithm. Uniformly distributed pseudo-random noise was added to simulate error in the image. The algorithm was proven to work even in cases in which the characters were extremely degraded by noise.
4. Khaled Almustafa, Rached N. Zantout , Hasan R. Obeid, "Pixel Density: Recognizing Characters in Saudi License Plates," Proceeding ISDA2010 Cairo, Egypt.
ABSTRACT
In this paper character recognition in Saudi Automobile License Plates is described. Due to special properties of Saudi license plates, simpler procedures as compared to the ones used for Lebanese plates have been developed. A limited character set for recognition enables the development of smaller recognition trees. The process relies on processing pixels along vertical and horizontal lines taken across the character. The developed procedure was applied to different characters taken from real license plates and the recognition rate was 100% for characters supported by the algorithm. Uniformly distributed pseudo-random noise was added to simulate error in the image. The algorithm was proven to work even in cases in which the characters were extremely degraded by noise.
5. Eltayeb Abuelyaman, Atikan Teber and Khaled Almustafa “Extension of Diffie- Hellman’s Secure5 Key Distribution Technique to Multipoint Broadcasting,” Proceeding of the 2010 World Congress in Computer Science, Computer Engineering, and Applied Computing (WORLDCOMP'10: July 12-15, 2010, USA).
ABSTRACT
This paper proposes a scheme for optimizing the overhead of secured digital contents broadcasting. The scheme minimizes the storage requirement of subscribers’ keys at the receiving end. It also minimizes the overhead associated with securing the contents of the carrier packet. The scheme extends the point to point Diffie-Hellman technique for securing key exchanges and generalizes it to multipoint environments. It guarantees as a worst case scenario, the same level of security claimed by its predecessors. Initial performance analysis suggests superiority of the proposed scheme over leading competitors in the market.
6. Serguei Primak and Khaled Almustafa, “Optimization of Pilot Locations in Adaptive MPSK Modulation in Rayleigh Fading Channel in Imperfect CSI,” Proceeding IEEEGCC09. Kuwait, 2009.
ABSTRACT
Performance of constant-power variable rate M-PSK schemes over Rayleigh fading channels in the presence of Imperfect Channel State Information (CSI) is investigated. Performance was for a single frame decoding and prediction in term of spectral efficiency and BER Vs. data bit locations. Assumption of negligible time delay between channel estimation and signal set adaptation was presented. It was shown that rate adaptation is the key to increasing link spectral efficiency.
7. Serguei Primak and Khaled Almustafa, “On the Covariance Function of a Mobile to Mobile Communication Link,” the IASTED International Conference on Modelling and Simulation (MS 2007). Montreal, Canada.
ABSTRACT
We suggest a model of a mobile to mobile communication link based on non-uniform two rings scattering environment. Expressions for time-space covariance functions are derived together with level-crossing rate and the average fade duration. Efficient simulator is adopted from the literature and used to evaluate performance of a simple 2×2 system.
8. Serguei Primak, Khaled Almustafa and T. Willink, “On Alamouti Scheme Performance in Spatially Correlated Fading and Pilot Assisted Channel Prediction,” the IASTED International Conference on Modelling and Simulation (MS 2007). Montreal, Canada.
ABSTRACT
In this paper, the performance of the Alamouti space-time code in time-varying spatially and time correlated Rayleigh fading channels with imperfect channel estimates is considered. Estimating filters are used to improve the accuracy of channel knowledge during the reception of data symbols between the pilot sequences of adjacent frames. The effects of different parameters of the estimating filter, such as filter length, filter type, causality, etc. and antenna geometry on the bit rate are presented. It is found that the use of estimation filters can improve the performance even for correlated channels, particularly using the Wiener filter.